page missing for forum member profile

[Monsieur OUXX]

I clicked on the link to the personal info under user "HAL" and I got this very official serious error message from Microsoft Forefront:

Network Access Message: The page cannot be displayed Explanation: There is a problem with the page you are trying to reach and it cannot be displayed.

Try the following:
Refresh page: Search for the page again by clicking the Refresh button. The timeout may have occurred due to Internet congestion.
Check spelling: Check that you typed the Web page address correctly. The address may have been mistyped.
Access from a link: If there is a link to the page you are looking for, try accessing the page from that link.

If you are still not able to view the requested page, try contacting your administrator or Helpdesk.

Technical Information (for support personnel)
Error Code: 500 Internal Server Error. The data is invalid. (13).
IP Address: 217.174.240.177
Date: 18/02/2015 10:29:14 [GMT]
Server: SRV-UL-TMG.alsy.fr
Source: web filter

More precisely, I was reading a conversation thread, and saw that message from user "HAL", with his picture on the left of the message , and clicked on his name just below his picture. (just like you could click on "monsieur ouxx" on the left of this message)
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[AGA]

Was it only that one page, on that one occasion?  Proxy services sometimes glitch of course, and you're the only person to ever mention this...